changing RC CAR fraquencies to 70MHZ

hi
i have RC car that can move back forth left right i do not know what frequency/ies are being used label with 40mhz if there if one frequency is being used i
want to change it to 70 mhz if two or more are being used then i want to
change then sequentially mean 70,72, or whatever but 70 to above
please help me how can i do this what kind of components do i need

yes its not easy.. first you need to detect the original range.. chinese stickers are usually fake.. you then need to fix a 70mhz band on both transmitter and receiver....but then vikas got a point i really want to know why you want to do that? that too on a ripped off RC?

RC Frequency is determined by a Quartz crystal: 1 for RX and 1 for TX. Both are not of the same value.
The cost of these Crystals are more than the RC unit itself, sometimes. ( minimum $10 + shipping )
If you do shell down the higher cost and procure them, then you have to modify/change the front-end Tuned circuit of the receiver and the Tank coil of the Transmitter. This is not the only thing , though.
Knowing the types of circuits in cheap RC remotes, most don't have a Reference crystal at all.

RC remotes have a Quartz Crystal that determine the Operating frequency- 1 for the TX and for the RX.
The cost of these crystals are sometimes greater than the Remote itself ( $10 + shipping)
If you do get the crystals at the higher cost, you have to modify the Front-end tuned circuit of the RX and the Tank Coil of the TX, among other things.
Knowing these cheap remotes, most of them don't have a crystal at all.